This application claims the benefit of the priority date of German application DE 102 55 462.5, filed on Nov. 25, 2002, the contents of which are herein incorporated by reference in their entirety.
The present invention is directed to optical components, and more particularly to an optical system arrangement and a method for producing such an optical arrangement.
Optoelectronic components, in particular lasers and photodetectors, are frequently accommodated or xe2x80x9chousedxe2x80x9d in so-called TO housings. The signals are input and output via contact-making pins that are passed through the housing and are connected to the components by means of bonding wires. The bushings for the contact-making pins are glazed and are routed coaxially, thus offering hermetic encapsulation for the sensitive optoelectronic components. Furthermore, the TO housing shape is relatively compact and has a low price, since it is a standard product that is mass-produced. In particular, lasers that are accommodated in TO46 housings have become established as a type of standard product for optical data transmission over short and medium distances in the range up to 2.5 Gigabits per second.
The data rates for optical telecommunications are, however, currently in the range of 10 Gigabits per second or more, so that the said TO housings can no longer be used directly for optoelectronic components. Lasers and photodetectors with data rates of 10 Gigabits per second or more are thus nowadays offered in special housings composed of metal or ceramic. These housings are optimized for high frequencies and offer the capability to integrate further electronics, such as driver components or preamplifier components in them. However, housings such as these are manufactured only in very small volumes, so that the prices for such housingsxe2x80x94also referred to as hybrid housingsxe2x80x94are considerably greater than the cost of a TO housing.
One aspect of the invention is based on the object of improving the electrical characteristics of an electrical arrangement of the type described initially. This includes, in particular, the aims of achieving a better frequency response, for example a higher cut-off frequency, than in the case of the already known electrical arrangements.
Accordingly, the invention provides for at least one of the contact-making pins which are passed through the housing to touch the mount device, and, in the area of the touching point, for a connection without any bonding wires to be provided between this at least one contact-making pin and at least one conductor track on the mount device.
One major advantage of the electrical arrangement according to the invention is that its frequency response is better than that of the already known electrical arrangements. The electrical arrangement according to the invention can thus be used to achieve a higher cut-off frequency since no bonding wire connection for electrical contact making is required between the contact-making pin and the mount device; this is because, in the arrangement according to the invention, the mount device and the at least one contact-making pin touch one another such that an electrical connection without bonding wires is possible in the area of the touching point. Bonding wires, such as those that are required for making contact between the mount device and the contact-making pin in the already known electrical arrangements, always have additional line inductances, which decrease the cut-off frequency. This is where the invention comes into play, by dispensing with bonding wires for making electrical contact between the contact-making pin and the mount device; according to the invention, this is achieved by the mount device being mounted on the housing base plate of the electrical arrangement such that it touches at least one contact-making pin which is passed through and allows an electrical connection without any bonding wires.
A further advantageous development of the arrangement according to the invention provides for the mount device to have an edge recess, whose contour is matched to the contour of the at least one contact-making pin, in the area of the touching point. The matching of the contours of the edge recess and of the contact-making pin result in a particularly large-area electrical connection between the electrical contact-making pin and the mount device, so that a particularly low-impedance and secure electrical connection is possible between the contact-making pin and the conductor track on the mount device.
In this context, it is regarded as being advantageous for the recess to be semicircular, because a semicircular recess on the one hand allows very simple adjustment and mounting of the mount device on the housing base plate and, on the other hand, it nevertheless allows a good electrical contact-making capability between the contact-making pin and the mount device.
In order to achieve a particularly large-area and thus low-impedance electrical contact between the mount device and the contact-making pin, it is regarded as being advantageous for the mount device to be metallized and/or to have a conductive contact-making layer in the area of the edge recess.
Another advantageous refinement of the electrical arrangement according to the invention provides for the mount device to have a contact-making hole in the area of the touching point, through which contact-making hole the at least one contact-making pin is passed. In contrast to the advantageous refinement of the invention as described above, in which the touching point between the contact-making pin and the mount device is located in the edge area of the mount device, the touching point in this refinement of the electrical arrangement is arranged in the internal area of the mount device.
In order to achieve a particularly large-area and thus low-impedance electrical connection between the contact-making pin and the mount device, it is in this context regarded as being advantageous for the inner area of the contact-making hole to be metallized and/or to have a conductive layer.
The electrical contact between the at least one conductor track on the mount device and the at least one contact-making pin can be made particularly easily and thus advantageously by means, for example, of conductive adhesive. However, instead of this, it is also possible to solder the at least one contact-making pin and the at least one conductor track on the mount device to one another in the area of the touching point.
Soldering between the at least one contact-making pin and the at least one printed circuit board on the mount device can be achieved, for example, by means of a solder ball or solder platelet, either of which is applied to the at least one contact-making pin, and thus also to the at least one conductor track, in the area of the touching point.
As already indicated above in conjunction with the already known prior art, particularly stringent requirements for cut-off frequencies occur especially in the area of optoelectronics. It is thus regarded as being advantageous for the electrical component to be an electro-optical component, in particular an optical transmitting and/or receiving element. The electrical component may thus, for example, be a laser or a photodetector.
With regard to the at least one contact-making pin passing through the housing base plate, it is regarded as advantageous for the bushing to be a glazed coaxial bushing. Glazed coaxial bushings have the advantage that they allow the housing to be hermetically sealed.
Apart from this, it is regarded as being advantageous for the housing of the electrical arrangement to be a TO housing, in particular a TO46 housing, since housings such as these are available at very low cost since they are mass-produced, and, in consequence, this also reduces the costs of the overall electrical arrangement.
The mount device may advantageously be formed by a circuit mount.
The circuit mount is advantageously composed of silicon, of ceramic, of an organic material or of a metal that is provided with an isolation layer. Both metal and silicon have particularly high thermal conductivity, so that these materials allow the heat that is produced by the electrical component to be thermally dissipated particularly well.
Particularly high electrical cut-off frequencies can be achieved by removing or replacing, as much as possible, all the avoidable bonding wire connections; it is thus regarded as being advantageous for an electrical component having at least two connections for each of these connections to be electrically connected to a conductor track. In addition, it is advantageous for the mount device to touch at least two contact-making pins, which are routed to the exterior, and for the connection between the two conductor tracks and between the two contact-making pins to have no bonding wires.
In order to achieve as high a cut-off frequency as possible for the electrical arrangement, another aspect of the invention provides for the mount device to be mounted on a housing base plate such that the mount device touches at least one contact-making pin, which is routed to the exterior. The invention further provides, in the area of the touching point, for a connection without any bonding wires to be produced between the at least one contact-making pin and the at least one conductor track on the mount device.
With regard to the advantages of the method according to the invention, and with regard to the advantages of the advantageous refinements of the method according to the invention, reference is made to the above statements relating to the electrical arrangement according to the invention, since the advantages of the method according to the invention essentially correspond to the advantages of the arrangement according to the invention.